1. Field of the Invention
The present invention relates to an apparatus and a method for inspecting leads of an IC, and more particularly, to an apparatus and a method for precisely and automatically inspecting leads of an IC.
2. Description of the Prior Art
When the intervals between the leads of an IC and arrangement thereof are not even, the leads may get loose from a setting table while they are welded, which may cause a defect in electrical connection thereof. Thus, ICs have to be inspected before being installed on a PCB, and therefore, a variety of methods for inspecting the status of leads of an IC have been proposed.
FIG. 6 is a schematic partial perspective view of an apparatus for inspecting leads of an IC disclosed in U.S. Pat. No. 5,162,866. As shown in the figure, the conventional apparatus 61 for inspecting leads of an IC complises a setting table 57 on which ICs 51 are placed, a supporting part 63 for supporting the setting table 57, an optical image recognition part 65 disposed above the supporting part 63, and an image processor (not shown) for implementing the image of an inspection area on the basis of the output signals of the optical image recognition part 65.
The optical image recognition part 65 inspects the status of leads 53 of the IC 51 placed on the setting table 57. The optical image recognition part 65 has a laser beam source 67 and an optical sensing element 69. The laser beam source 67 projects a scan beam toward the IC 51 on the setting table 57, and the optical sensing element 69 receives the light reflected from the leads 53 of the IC 51. The optical image recognition part 65 is fixed to an arm 71, and the arm 71 can be moved horizontally and vertically by a driving device which is not shown.
In the conventional inspecting apparatus 61 having such a construction, when the setting table 57 on which the IC 51 is placed is supported by the supporting part 63, the optical image recognition part 65 is disposed above the setting table 57 by a manual operation of an operator or by a program stored in a control part. Then, the operator observes the image of the IC 51 implemented on the image processor while moving the optical image recognition part 65 with respect to the setting, table 57. When a position at which an optimal image can be achieved is detected during the observation, the operator disposed the optical image recognition part 65 on that position. In order to inspect precisely the intervals and arrangement of the leads 53, it is most important to dispose the optical image recognition part 65 at an optimal position.
Meanwhile, when the optical image recognition part 65 is disposed at the optimal position, the control part (not shown) moves the optical image recognition part 65 along a predetermined scan line. The laser beam source 67 projects the scan beam toward the leads 53 while the optical image recognition part 65 is moving, and the optical sensing element 69 receives the light reflected from the leads 53. The amount of reflected light received by the optical sensing element 69 valies according to the intervals and the arrangement of the leads 53, and the optical image recognition part 65 outputs pulses having the amplitude corresponding to the amount of the reflected light received by the optical image recognition part 65. The image processor implements the image of the leads 53 according to the output signal of the optical image recognition part 65, so the operator can determine the quality of the leads 53 of the IC 51.
Meanwhile, another type of apparatus for inspecting leads of an IC has been proposed which can detect the defect thereof automatically by comparing the output signals of the optical sensing element 69 with reference data about the quality of the leads of an IC.
Recently, the electrical appliances become small-sized and performance thereof becomes high, so the size of the IC 51 becomes smaller. Therefore, in order to inspect the intervals and arrangement of the leads 53 of an IC 51 with the conventional inspecting apparatus 61, the operator has to precisely control the distance between the IC 51 and the optical image recognition part 65 manually. Therefore, the inspection speed is low, and the preciseness of the inspection is lowered.